Device for making an internally coated tubular blank



June 11, 1968 J. KILGALLON DEVICE FOR MAKING AN INTERNALLY COATED TUBULAR BLANK Filed Nov. 17, 1964 2 Sheets-Sheet 1' INVENTOR. jof/fl ffzZya/Zon June 11, 1968 J. KILGALLON DEVICE FOR MAKING AN INTERNALLY COATED TUBULAR BLANK 2 Sheets-Sheet :3

Filed Nov. 17, 1964 INVENTOR. 70/70 fflilgaZ/oxz m can? United States Patent Ofice 3,337,348 Patented June 11, 1968 3,387,348 DEVICE FOR MAKING AN INTERNALLY COATED TUBULAR BLANK John Kilgallon, Lachine, Quebec, Canada, assignor to Crompton & Knowles Corporation, Worcester, Mass, a corporation of Massachusetts Filed Nov. 17, 1964, Ser. No. 411,939 9 Claims. (Cl. 25-38) ABSTRACT OF THE DISCLOSURE A tubular blank is fed successively over a form-fitting mandrel and therefrom spaced, substantially form-fitting plunger having a shank which extends with clearance through an aperture in the mandrel to form therein a passage for a liquid coating material from a source to a reservoir formed between the mandrel and plunger for interiorly coating the passing blank at the reservoir.

This invention relates to stock coating in general, and to a device for and a method of internally coating tubular blanks in particular.

The present invention pertains to coating, with plastic or any other material in transferrable liquid form, the interior of a tubular blank of any length and of most any material, such as metal, paper, fabric or another kind of plastic, or any combination of these or similar materials, for further fabrication of the blank thus coated into products of many kinds.

It is the primary aim and object of the present invention to provide for internally coating a tubular blank in a continuous operation regardless of the length of the blank.

It is thus another object of the present invention to provide, directly on a tube former and internally of a formed blank passing therefrom, a device for applying to the inside of the passing blank liquid coating material of coating thickness, with the coating material being supplied to the device from a source outside the tube former advantageously over a short path through the latter.

It is a further object of the present invention to devise a method of internally coating a tubular blank, which comprises placing part of the blank over a substantially form-fitting plunger to define in the blank ahead of and next to the plunger a cylinder-like space, maintaining in said space a bath of coating material in contact with the entire inner blank periphery thereat, and internally coating the blank by passing the same over the bath and the succeeding plunger rearwardly thereof.

Another object of the present invention is to carry the aforementioned blank-coating method further to a continuous coating method which comprises, continuously forming a tubular blank on a mandrel of preferred hor izontal disposition and displacing the blank from the mandrel at the rate of its formation thereon, leading the blank being displaced over a substantially form-fitting plunger, and internally coating the blank by maintaining within the blank between the mandrel and plunger a bath of coating material in contact with the entire inner blank periphery thereat.

A further object of the present invention is to arrange the aforementioned coating device so that the same Will perform in accordance with the continuous coating method just mentioned, by arranging the plunger just behind the mandrel and providing it with a mounting shank which extends with clearance in a longitudinal passage in the mandrel through which to supply the bath between the plunger and mandrel with coating material from an outside source.

It is another object of the present invention to keep the coating material of the bath between the mandrel and plunger at proper coating consistency, especially if the coating material is molten plastic, by providing an electric heating element or elements in the plunger, and extending the mounting shank of the plunger through the passage in the mandrel and making it hollow so as to serve as a conduit through which to lead the requisite electrical conductors to the heating elements.

It is a further object of the present invention to shape and dimension the aforementioned plunger so as to serve as a forming mandrel for the internal blank coating in point of its thickness and uniformity peripherally throughout.

Other objects and advantages will appear to those skilled in the art from the following, considered in conjunction with the accompanying drawings.

In the accompanying drawings, in which certain modes of carrying out the present invention are shown for illustrative purposes:

FIG. 1 is a fragmentary longitudinal section through a device embodying the present invention;

FIG. 2 is a fragmentary cross-section through the device as taken on the line 2-2 of FIG. 1;

FIG. 3 is a cross-section through the same device as taken on the line 3-3 of FIG. 1;

FIG. 4 is another fragmentary cross-section through the device as taken on the line 4-4 of FIG. 1;

FIG. 5 is a fragmentary longitudinal section through a tubular blank to be plastic-coated in the device of FIG. 1; and

FIG. 6 is a fragmentary longitudinal section through a device embodying the invention in a modified manner.

Referring to the drawings, and more particularly to FIG. 1 thereof, the reference numeral 10 designates a device for internally coating a tubular blank, and in this instance a device for continuously producing an internally coated tubular blank. To this end, the device 10 comprises continuous blank-forming means 12 and coating applying means 14.

The blank-forming means 12 includes a mandrel 16 on which a blank B is continuously formed, in this instance by helically winding strip stock s thereon usually at spaced stations along the mandrel 16 to form successive helicalwound stock layers which are bonded together at their interfaces in the course of their wind-on on prior application of cement to the proper face of each strip s. Thus, there is shown in FIG. 1 the application of a final layer L of strip stock on top of the last-wound layer L with the strip s of the final layer vL being wound onto the previous layer L in this instance in anticlockwise direction as viewed from the right end of FIG. 1, and the blank B being moved forward in the direction of the arrow 18 by suitable power feed means (not shown) which displace the blank B from the mandrel 16 at the rate of its continuous formation thereon. Accordingly, the blank-forming means 12 also includes power-driven strip winders of any conventional type (not shown). The mandrel 16 is suitably mounted so as to be disposed with its axis x preferably substantially horizontally for easiest installation and maintenance of the equipment involved in the coated blank production as well as for the production of a continuous blank of most any length within the lengthwise limits of the available shop space.

The coating applying means 14 is arranged internally of the formed blank B on and immediately rearwardly of the mandrel 16, and comprises a plunger 20 and an endless bath [2 of liquid coating material C between the plunger 2t] and mandrel 16 (FIGS. 1 and 3), with the bath being continuously supplied with coating material and the coating material of the bath being kept under sufiicient constant pressure to contact the inner blank surface 22 peripherally throughout over the axial extent of the bath and thus apply the internal coating C to the blank B as the latter passes continuously over the bath b and succeeding plunger 20. The bath b is contained in an endless reservoir 24 which is formed by the mandrel 16 and the plunger 20 with its cross-sectionally reduced shank 26 between the axially spaced mandrel and plunger, and the bath b is supplied with coating material through a longitudinal passage 28 in the mandrel 16. The plunger 20 is mounted on the mandrel 1.6 through intermediation of its shank 26 the end 3%) of which rests on a seat 32 within the mandrel for locating the plunger in spaced and coaxial relation with the mandrel, with the shank end 30 being held on the seat 32 in any suitable manner such as by a driven pin or pins (not shown). The shank 26 of the plunger 20 thus extends into the passage 23 in the mandrel 16 and has clearance therefrom peripherally throughout so that the passage 28 is cross-sectionally ringshaped at 34 over the axial extent of the plunger shank 26 therein. The mandrel 16 is in this instance made up of successive sections 36 and 38 of which the rear section 38 is at 40 threaded on the front section 36. The seat 32 for the plunger shank 26 is in this instance provided on an insert sleeve 42 which is fittedly received at 44 in the mandrel section 38, and is provided with a collar 46 which is locked in place between an annular shoulder 48 in the mandrel section 38 and the adjacent end surface 50 of the other mandrel section 36. The part of the mandrel passage 28 over the axial extent of the front mandrel section 36 is formed in this instance by a conduit 52 which at its rear end is threadedly received at 54 by the insert sleeve 42 and is mounted in any suitable manner at its opposite end (not shown) which is in communication with a source of coating material under proper pressure. With the seat 32 for the plunger shank 26 being arranged internally of the passage 28 in the mandrel 16 in the first place, and provided on the insert sleeve 42 in the mandrel in the second place, continuity of the mandrel passage 28 at the sleeve 42 is achieved in this instance by radial slots 56 in the latter (FIGS. 1 and 4). The seat 32 is formed in this instance by a machined frusto-conical end face of the sleeve 42, and the plunger shank end 30 is correspondingly machined so as accurately to fit on the seat 32 for equally accurate location of the plunger 20 relative to the mandrel 16.

The tubular blank B formed on the mandrel 16 in the described manner may have wound layers of most any strip stock s, such as metal, paper or fabric, for example,

or any combination of these or other materials, and the coating material C may be polymeric, plastisol, organisol, emulsion, suspension or of any other transferrable liquid form. The exemplary blank B (FIGS. 1 and may thus be a cardboard tube for further fabrication into many products, with the blank being formed by successive layers of wound paper strip s, and the blank may be internally coated in this instance with a plastic such as polyethylene, for example. Accordingly, in order to thus internally coat the tubular blank B, the coating material is a plastic which must, at its source beyond the mandrel 16 as well as on its conductance through the mandrel to, and confinement in, the bath b, be in molten state. To this end, the plastic source may be a plastic extruder which is with its discharge end in communication with the mandrel passage 28. While the path of the molten plastic from the source through the mandrel to the bath is kept as short as possible to avoid undue chilling of the molten plastic, it is nevertheless advisable to provide for heating, and it is in many instances imperative to heat, the plastic of the bath to restore or bring it to the correct consistency for coating the interior of the blank on contact therewith and have the plunger size the plastic coating C to any desired thickness uniformly throughout (FIGS. 1 and 2), with the plunger being crosssectionally shaped and dimensioned accordingly. To this end, the

plunger 20 has in this instance a ring-like recess 60 in which is received an electric heater element 62 (FIGS. 1 to 3). To supply the heater element with current through an electrical conductor, there is provided a tube or sleeve 64 which extends from the plunger 62 through the mandrel passage 28 and molten plastic source therebeyond and serves as a conduit through which to lead the electrical conductor (not shown) to the heater element. With the plastic source being in this instance a plastic extruder, the same will require a side-delivery head, such as the head 66 in FIG. 6, in order that the tube 64 may pass therethrough to the outside thereof for accessibility to a conductor and its connection with an outside power source. The side delivery head 66 in FIG. 6 which may be entirely conventional, has a characteristic elbow passage 68 with transverse branches 70 and 72 of which branch 70 would be in communication with the mandrel passage 23 (FIG. 1), while the other branch 72 is in communication with the discharge end 74 of the extruder 76 (FIG. 6). With the plunger 20 being fast on the tube 64 and the latter passing in the exemplary installation through a side-delivery head of an extruder in or on which it is firmly mounted, as at 78 in FIG. 6, for example, it is entirely feasible, and even preferred, that the tube 64 solely retains the end 30 of the plunger shank 26 on its seat 32 (FIG. 1). Also, the tube 64 is of a size to pass through the mandrel passage 28 (FIG. 1) and succeeding passage in the side-delivery head of the extruder (FIG. 6) with peripheral clearance throughout.

In operation, strip stock s is continuously wound on the mandrel 16 to build up and form the blank B, and the latter is continuously fed from the mandrel in the direction of the arrow 18 (FIG. 1) at the rate of its formation. The thus continuously forming blank B passes from the mandrel over the molten plastic bath b and succeeding plunger 20 where the plastic coating C is applied and sized, respectively, with the plunger 20 being of a length to permit sufiicient initial solidification of the plastic coating C to sustain itself on leaving the plunger for its final solidification. The plastic coating C thus applied to the blank B also closes whatever narrow gaps g may remain between the substantially butted turns of the strip stock of the first layer L" of the blank (FIG. 5). With the exemplary molten plastic of the bath b being derived from an extruder and, hence, being under considerable pressure even at low extrusion pressure, it may well be imperative to back a tubular blank, such as the exemplary cardboard blank B of relatively small wall thickness and, hence, low burst resistance, at least over the axial extent of the bath b, as by passing the blank through a fixed sleeve of adequate strength thereat (not shown).

While in the production of the exemplary plasticcoated blank B the plunger 20 is preferably provided with the electric heater element 62, requiring the tube 64 for a conductor conduit, the tube 64 or a solid rod in lieu thereof may be used, in coating a blank with a material other than plastic that requires no heating by the plunger and, hence, no heater element therein, for the sole purpose of retaining the end 32 of the plunger shank on its seat 32. In that case, the mandrel passage 28 communicates, not with a side-delivery head of an extruder as in FIG. 6, but rather with a simple elbow conduit to which the tube or rod may be secured and which leads from the source of coating material under proper pressure.

While in the described operation the blank B is formed by winding strip stock on the forming mandrel, FIG. 6 shows a modified device 10a for continuously producing an internally coated plastic tubular blank which in this instance is internally coated with plastic of a different kind. Thus, the device 10a may in all respects be like the described device 10 of FIG. 1, except that the blankforrning means 12a is in this instance an extrusion die 80 in a side-delivery head 82 of a plastic extruder 84, with the die 80 having inner and surrounding outer companion members 86 and 88 of which the outer member 88 is formed by the delivery head 82. The discharge end 90 of the extruder 84 is in communication with a passage 92 in the delivery head 82 which leads to a helical passage 94 and a continuing ring-like passage 96 that in turn leads to the die aperture 98 in which the plastic blank Ba is formed. The mandrel 16a is an extension of the inner die member 86, being in this instance a separate part suitably mounted at 100 on the inner die member. The side-delivery head 82 and die 80 therein may be conventional, and may in all respects be like or similar to the head and die shown in the patent to Bonner, No. 3,026,- 565, dated Mar. 27, 1962.

In operation of the device, the plastic blank Ba is continuously extruded at the die aperture 98 and is passed over the mandrel 16a at the rate of its formation, with the mandrel 16a being of sufiicient length to permit the passing plastic blank thereon substantially to solidify before passing over the bath ba, so that the plastic coating Ca applied thereat and sized as to uniform thickness by the plunger a will retain what ever characteristic or characteristics it has that prompted its application to the plastic blank in the first place.

With the exemplary coating material Ca being molten plastic of a preferably different kind than that of the blank Ba, the bath ba is supplied with molten plastic Ca through the passage 28a in the mandrel 16a and inner die member '86 from the side-delivery head 66 of the extruder 76. The plunger 20a is preferably heated, or at least capable of being heated, to restore or bring the plastic Ca of the bath ba to proper consistency for coating the blank. To this end, the plunger 20a has in this instance an internal chamber 102 to which leads the tube 64a, not for leading a conductor to an electric heater element in the plunger, but rather for conducting to the plunger chamber a heat-exchange medium, such as steam or hot water, with the plunger chamber 102 being also in communication with another tube 104 which extends through the tube 64a with peripheral clearance therefrom and serves as a return path for the medium from the plunger chamber 102, thus permitting circulation of the medium through the plunger chamber and also providing for heat-exchange between the medium and the plastic coating material on the path of the latter through the mandrel passage 28a.

While the devices 10 and 10a are shown to produce an internally coated tubular blank of circular section, it is, of course, fully within the purview of the present invention to arrange the blank-forming means and the plunger to produce an internally coated tubular blank of any other suitable section. Also, while the devices 10 and 10a are described, and preferably function, to form a tubular blank which passes in substantially horizontal direction, it is also fully within the purview of the present invention to arrange these devices for forming a tubular blank and passing it in a direction inclined to a horizontal plane or substantially vertically. Thus, it is entirely possible to operate the device 10 of FIG. 1, for instance, by arranging it substantially vertically, with the blank-forming means 12 being above the plunger 20. However, substantially horizontal arrangement of this device is preferred for the reasons given earlier.

The present invention also involves a method for internally coating tubular blanks as well as for continuously producing an internally coated tubular blank, with the primary feature of the method being the maintenance in any manner of a bath of coating material in the blank itself to serve as a cylinder space just ahead of a plunger therein and in Contact with the entire inner blank periphery thereat, while passing the blank over the bath and succeeding plunger rearwardly thereof. Insofar as the continuous production of an internally coated tubular blank is concerned, the same involves continuously forming a tubular blank at a station and displacing it from this station at the rate of its formation thereat, leading the blank being displaced over a substantially form-fitting plunger, and internally coating the blank by maintaining within the blank between the station and plunger a bath of coating material in contact with the entire inner blank periphery thereat.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

What is claimed is:

1. A device for producing an internally coated tubular blank, comprising blank-forming means including a mandrel with a longitudinal through-passage; a plunger adapted slidably to receive a tubular blank with a substantial form-fit, said plunger having a cross-sectionally reduced shank extending into said passage with peripheral clearance therefrom and being mounted for the support of said plunger in spaced and coaxial relation with said mandrel, said mandrel and plunger with its shank defining between said mandrel and plunger an endless reservoir for coating material, and said passage leading to said reservoir; an elbow conduit with transverse branches of which one branch is in alignment and communication with said passage at the end thereof most remote from said reservoir; and a tube extending from the outside of said elbow conduit through said one conduit branch and passage with peripheral clearance therefrom and into said plunger to serve as a communication channel between said plunger and the outside of said elbow conduit.

2. A device for producing an internally coated tubular blank as set forth in claim 1, which further comprises electric heating means in said plunger, with said tube serving as a conduit for electrical conductor means to said heating means.

3. A device for producing an internally coated tubular blank as set forth in claim 1, in which said plunger has an internal chamber to which said tube leads, and said tube serves for conducting a heat-exchange medium to said internal plunger chamber.

4. A device for producing an internally coated tubular blank as set forth in claim 3, which comprises a further conduit extending with clearance through said tube and serving as a return path for said medium from said internal plunger chamber.

5. A device for producing an internally coated tubular blank as set forth in claim 1, in which there is provided in said mandrel internally of said passage therethrough a seat on which said shank rests with its end for location of said plunger in said spaced and coaxial relation with said mandrel, and said tube is secured to said plunger and to said elbow conduit and holds said shank end on said seat.

6. A device for producing an internally coated tubular blank as set forth in claim 5, in which said shank end and seat are of interfitting frusto-conical shape.

7. A device for producing an internally coated tubular blank as set forth in claim 1, in which said elbow conduit is a side-delivery extruder head with a plastic melt path to said passage for plastic-coating the blank.

8. A device for producing an internally coated tubular blank as set forth in claim 1, in which said blank-forming means comprises a side-delivery extruder head and a plastic extrusion die therein having inner and surrounding outer companion die members defining a ring-shaped die aperture, of which said inner member has an extension forming said mandrel, with said passage extending through said inner die member and extension thereof, and said elbow conduit is a side-delivery extruder head with a plastic melt path to said passage for coating the blank r with plastic of a kind different from that of the blank.

References Cited UNITED STATES PATENTS 2,126,556 8/1938 Hughes 118408 X 2,194,701 3/1940 Harrison 118408 X Stephens 117-95 X Brant 118408 Bonner 1814 Pistole et al. 118-408 McLean 118-408 X ALFRED L. LEAVITT, Primary Examiner.

A. G. GOLIAN, Assistant Examiner. 

